A recent report from Gamasutra revealed that Blizzard Entertainment's successful MMO, World of Warcraft, has old over 8.6 million copies of the game and its expansions in the U.S. alone. The sales have resulted in an estimated revenue of $258 million, not including the amount earned from monthly subscriptions.

Following the revelation that The Sims 3 sold more than 800,000 copies in its first month at U.S. retail, Gamasutra followed up with NPD to find out how well WoW -- perhaps the only retail competitor to The Sims series over the past few years -- has fared.

The NPD Group rolled up multiple SKUs of the massively popular PC online game and its expansion packs since its November 2004 launch to arrive at the 8.6 million figure.

No information on average sale price across all versions was provided. But presuming $30 for each unit sold (the core game currently retails at $19.95; expansion packs and compilations for as much as $39.95), it amounts to as much as $258 million total from U.S. retail alone.

The statistics provided by NPD included the base World of Warcraft, plus the Collectors Edition version, the expansion pack-bundling Battle Chest, and the two standalone expansions: The Burning Crusade and Wrath Of The Lich King.